Bro, just get out and do stuff you like to do. If you like reading, go to a book store and hang out. If you like to dance, who cares if you look goofy or not. Just do it, etc, etc, etc. Thats the best way to stay relaxed. Aggression is a problem for me when I am around the 'wrong' people, but otherwise I am all laughs and smiles. For me the gym, spending time with my fiance, movies and cruising with my windows down on a warm day/night all help my aggression. Oh, and music too! Nothing angry though, unless I am in the mood for that stuff! Otherwise it just makes it worse!
If it continues no matter what you do, then you might need to take a light medication. Zoloft, Paxil, etc, etc. Just try a few things out, and see if it calms you down/helps make you more happy. Good luck bro!